This invention is directed to a hook and loop fastener. A number of fastening systems, such as diaper fastening systems, incorporate a hook and loop system for easy fastening and release. The hook component typically includes a flat plastic sheet laminate with a number of protruding hooks that engage (i.e., mesh or interlock) with a number of loops protruding from a corresponding loop component. While many of the individual hooks engage with individual loops, many of the individual hooks and the individual loops are merely in contact with one another with no engagement between them. These non-engaged hooks and loops neither help nor hinder overall fastening strength between the hook component and the loop component.
There is a need or desire for a hook and loop fastener wherein all or most of the individual hooks and loops (including those which touch but are not engaged) contribute to the fastening strength between the hook component and the loop component.
The present invention is directed to a hook and loop fastener whose components have an increased coefficient of friction compared to conventional nonwoven hook and loop fasteners. By increasing the coefficient of friction, the fastening performance of the hook and loop fastener is increased by increasing the forces required to separate both engaged and contacting (but not engaged) hooks and loops. Essentially, the hook fastener and the loop fastener remain engaged or in contact for a longer period of time than conventional hook and loop fasteners due to the increased coefficient of friction which requires a greater force of separation.
In one embodiment of the invention, the coefficient of friction can be increased by adding a tackifier to the hook and/or loop components, for instance, in the hook forming process and/or the loop forming process. In another embodiment, a friction modifier can be painted onto the surface of hooks and/or loops already formed. In another embodiment of the invention, multi-component fibers can be extruded to form a loop component. The multi-component fibers can include a fiber type that enhances strength and a fiber type that has less strength but has a higher coefficient of friction. In yet another embodiment of the invention, multi-shaped, multi-lobal, or irregular-shaped fibers are used to increase the total friction by increasing the contact surface area and providing edges. In still another embodiment of the invention, surface bloom additives can be processed into the hook and/or loop structures in such a way as to increase the coefficient of friction of the fastener after blooming is complete.
Any of these improvements to the hook and loop fastener, or a combination of these improvements, result in a hook and loop fastener having increased friction between the hooks and loops, such that the individual hooks and loops facilitate engagement between the hook component and the loop component, even between non-engaged hooks and loops in contact with one another.
With the foregoing in mind, it is a feature and advantage of the invention to provide a hook and loop fastener having increased friction between the hooks and loops.